I was just pondering the use of the words. I had remembered reading a story in a college English class about dumpster diving and in the story they jumped inside and hung out (yuk, yuk, yuk) as they searched. I also just saw the "Once Upon a Time in Hollywood" movie and there is a scene where the Manson devotees are dumpster diving.
The concept of Dumpster Diving?
A person 'Dives' head first into a pool of water as a definition of 'Diving'.
Then we use the old adage to 'Dive in Head First' when encouraging someone to tackle a project by giving it All they have.
So using those examples, we could determine that the 'Diving' part is going in 'head first' and/or 'giving it all you have' and therefore could also be construed as leaning over and reaching far down in and/or climbing all the way in, since that is also going in 'head first' and 'giving it all you have'.
Then, there are people that literally 'Dive in Head First' into the big dumpsters. If they do not have something to stand on, to which they could Climb into the dumpsters, they may literally have to go 'all the way in' by 'Diving in Head First' to reach something or look under something.
With trash being inside the dumpster, it would be easier for the 'Diver' to climb back Out than it was to 'Dive in Head First'.
One of our children has worked with a non profit that works with the homeless and she is therefore familiar with the ways that the homeless attempt to provide for themselves. Our child worked with local metropolitan restaurants and they now bag up leftover food from the kitchen each day and Give it to the homeless, so that the homeless do not have to dive into the dumpsters for then 'unsanitary' food.
Point being, there has been Dumpster Diving all over the world for Many years. They reach in, they turn over, and they climb into all sorts of trash disposal containers of all sizes and shapes and it is All called Dumpster Diving.
With a MOO MOO here and a MOO MOO there.